1. Field of Invention
The present invention relates in general to an electrical circuit breaker provided with a modular contact system. More particularly, the present invention relates to a modular contact system made up of a multiplicity of single pole breaking modules having many different sizes, through simple parallel connection of individual single pole modules.
2. Description of Related Art
Multi-pole circuit breakers comprising a modular array of single-pole circuit breakers connected together by means of fasteners are well known in residential applications. U.S. Pat. No. 5,172,087 entitled xe2x80x9cHandle Connector for Multi-Pole Circuit Breakerxe2x80x9d describes such a multi-pole circuit breaker that incorporates an improved operating handle to integrate the separate single pole-handles into one effective operating handle. The overall width of the multi-pole circuit breaker is the sum of the individual single pole circuit breaker widths.
U.S. Pat. No. 6,326,868 entitled xe2x80x9cRotary Contact Assembly for High Ampere-Rated Circuit Breakers,xe2x80x9d herein incorporated by reference, describes single pole rotary contact arm assemblies ganged together to form a multi-pole circuit breaker. Interconnection of the contact arm assemblies with the operating mechanism is achieved by means of an elongated pin, thereby enabling a single mechanism to operate all single pole rotary contact arm assemblies. The rotary arrangement of the contact arms produces two arcs in series during a short circuit interruption, which rapidly and effectively extinguishes the short circuit current to disconnect the protected circuit.
For circuit breaker applications requiring high quiescent ampere ratings, the use of a larger circuit breaker with proportionately larger single pole components is well known and is described in U.S. Pat. No. 5,424,701 entitled xe2x80x9cOperating Mechanism for High Ampere-Rated Circuit Breakers.xe2x80x9d Another method of serving high quiescent ampere rated applications without increasing the size of the single pole components is by adjoining two standard sized circuit breakers and connecting adjacent poles in parallel. Such a twinned arrangement is described in U.S. Pat. No. 4,884,047 entitled xe2x80x9cHigh Rating Multi-pole Circuit Breaker Formed by Two Adjoined Molded Cases.xe2x80x9d The overall width of the twinned multi-pole circuit breaker is the sum of the individual multi-pole circuit breaker widths.
Multiple rotary contact arm assemblies having a low quiescent ampere rating are connected in parallel to form a single pole circuit breaker module having a high quiescent ampere rating, higher than the rating of its individual components. Ganging together these single pole circuit breaker modules, which comprise standard parts and modular assemblies, forms an economical and compact multi-pole circuit breaker having a high quiescent ampere rating.
The invention offers advantages of both a rotary contact arm assembly and a modular construction. The rotary contact arm configuration, which produces two arcs in series, provides an effective means for rapidly suppressing and extinguishing short circuit currents, and the single pole module, with parallel connected low ampere rated contact arms, provides an economical and compact means of achieving a high ampere rating.
According to the invention, a circuit breaker, comprising a circuit breaker housing and a first and second current path housing arranged within the circuit breaker housing. A first current path is arranged within the first current path housing and is connected to the protected circuit. A second current path is arranged within the second current path housing and is electrically connected in parallel to the first current path and is also connected to the protected circuit. An operating mechanism is arranged within the circuit breaker housing for disconnecting the protected circuit upon occurrence of an overcurrent condition in the protected circuit. A trip unit is arranged within the circuit breaker housing for articulating the operating mechanism upon occurrence of the overcurrent condition.